Transflective liquid crystal device and electronic apparatus using the same

ABSTRACT

The invention provides a transflective liquid crystal device and an electronic apparatus using the same which do not cause a non-uniformity in the substrate gap, even though a layer-thickness adjusting layer is formed so that the layer thickness balance of a liquid crystal layer between a transmission display region and a reflection display region is optimized thereby. Below a counter electrode of a counter substrate of a transflective liquid crystal device, a color filter for transmission display, being thin and having a wide chromaticity region, is formed in a transmission display region, and a color filter for reflection display, being thick and having a narrow chromaticity region, is formed in a reflection display region. Further, the interval between a TFT array substrate and the counter substrate is adjusted by a columnar protrusion formed on the TFT array substrate, and a gap material is not dispersed between the TFT array substrate and the counter substrate.

BACKGROUND OF THE INVENTION

[0001] 1.Field of Invention

[0002] The present invention relates to a transflective liquid crystaldevice having a reflection display region and a transmission displayregion in one pixel. The invention also relates to electronicapparatuses including the same.

[0003] 2. Description of Related Art

[0004] Related art liquid crystal devices that are capable of displayingimages in both a transmission mode and a reflection mode are referred toas transflective liquid crystal devices, and can be used in manyapplications.

[0005] In such a transflective liquid crystal device, as shown in FIG.21, an active matrix-type transflective liquid crystal device includes aTFT array substrate 10 (first transparent substrate) having atransparent pixel electrode 9 a (first transparent electrode) and apixel-switching TFT (Thin Film Transistor) 30 formed on the surface, acounter substrate 20 (second transparent substrate) having a counterelectrode 21 (second transparent electrode) and a color filter 24, and aliquid crystal layer 50 held between the substrates 10 and 20. Thesubstrate gap between the TFT array substrate 10 and the countersubstrate 20 is defined by dispersing gap material 5 having apredetermined particle size on the surface of one of the substrates, andthen sealing the TFT array substrate 10 and the counter substrate 20 bysealing material (not shown).

[0006] In such a liquid crystal device structured as above, the TFTarray substrate 10 includes a light reflecting film 8 a having areflection display region 100 b formed in a pixel 100 in which a pixelelectrode 9 a faces the counter electrode 21, a transmission displayregion 100 c formed in the remaining region (light transmitting window 8d) where the light reflecting film 8 a is not formed.

[0007] Therefore, with regard to the light emitted from a backlightapparatus (not shown) disposed on the back side of the TFT arraysubstrate 10, the light incident into the transmission display region100 c, as indicated by arrow LB, is incident from the TFT arraysubstrate 10 into the liquid crystal layer 50, and is light-modulated inthe liquid crystal layer 50, and then is emitted from the countersubstrate 20 as a transmission display light to display images(transmission mode).

[0008] Further, with regard to the external light incident from thecounter substrate 20, the light incident into the reflection displayregion 100 b, as indicated by arrow LA, passes through the liquidcrystal layer 50, reaches the light reflecting film 8 a, is reflectedfrom the light reflecting film 8 a, passes through the liquid crystallayer 50 again, and then is emitted from the counter substrate 20 as areflecting display light to display images (reflection mode).

[0009] When performing the light modulation, if a twist angle of aliquid crystal is set to be small, the changes of the polarization stateis shown as a function of multiplying the difference of an index ofrefraction Δn by the layer thickness “d” of the liquid crystal layer 50(retardation (Δn·d)), and therefore, if the value is enhanced oroptimized, a visibility of display becomes better.

[0010] However, in the transflective liquid crystal device, since thereflection display light passes through the liquid crystal layer 50twice, while the transmission display light is emitted by passingthrough the liquid crystal layer 50 once, it is difficult to optimizethe retardation (Δn·d) in both of the transmission display light and thereflection display light. Therefore, if the layer thickness “d” of theliquid crystal layer 50 is determined such that the display visibilityin the reflection mode is enhanced, the display in the transmission modeis sacrificed. Or if the layer thickness “d” of the liquid crystal layer50 is determined such that the display visibility in the transmissionmode is enhanced, the display in the reflection mode is sacrificed.

[0011] Therefore, with regard to the TFT array substrate 10, a thicklayer-thickness adjusting layer can be formed below the light reflectinglayer 8 a defining the reflection display region 100 b, and the layerthickness “d” of the liquid crystal layer 50 in the reflection displayregion 100 b be made thinner than the layer thickness “d” of the liquidcrystal layer 50 in the transmission display region 100 c.

[0012] Such a related art method is disclosed in Japanese UnexaminedPatent Application Publication No. 61-173221.

SUMMARY OF THE INVENTION

[0013] However, if the retardation (Δn·d) is enhanced or optimized byforming the layer-thickness adjusting layer, an unevenness is formed onthe surface of the substrate due to the layer-thickness adjusting layer.As a result, even though trying to control the TFT array substrate 10and the counter substrate 20 by dispersing a gap material 5 on thesurface of the counter substrate 20, or when assembling a liquid crystaldevice, the gap material comes into a concave portion generated due tothe layer-thickness adjusting layer so that the non-uniformity of thesubstrate gap occurs during the process of manufacturing a liquidcrystal device or after the liquid crystal device is manufactured, whichresults in a problem in which the retardation (Δn·d) cannot be held inan enhanced or optimum state.

[0014] Furthermore, if the thick layer-thickness adjusting layer isformed on the TFT array substrate 10 in spite of a photolithographyprocess performed to form a TFT to provide pixel 30 switching or thelight reflecting film 8 a, a considerable difference of altitude or stepoccurs on the TFT array substrate 10. As a result, the exposurepreciseness, etc. of the photolithography process is considerablylowered, and step fragments or film residues are generated so that thereliability of the liquid crystal device or the production yielddecreases.

[0015] The present invention addresses or solves the above and/or otherproblems, and provides a transflective liquid crystal device and anelectronic apparatus using the same, in which the non-uniformity of thesubstrate gap is not generated even when the layer thickness balance ofthe liquid crystal layer between the transmission display region and thereflection display region is enhanced or optimized by thelayer-thickness adjusting layer.

[0016] Further, the present invention provides a transflective liquidcrystal device and an electronic apparatus using the same in which theexposure preciseness is not lowered when forming a pixel switchingelement, etc. by using a photolithography technology, even when thelayer thickness balance of the liquid crystal layer between thetransmission display region and the reflection display region isenhanced or optimized by the layer-thickness adjusting layer.

[0017] To address or solve the above, the present invention provides atransflective liquid crystal device including a first transparentsubstrate having first transparent electrodes and pixel switchingelements formed on the surface in a matrix, a second transparentsubstrate having second transparent electrodes formed on the surface,facing the first transparent electrodes, and a liquid crystal layer heldbetween the first transparent substrate and the second transparentsubstrate, and a light reflecting layer is formed on the firsttransparent substrate, the light reflecting layer having a reflectiondisplay region in a pixel in which the first transparent electrode facesthe second transparent electrode, and a transmission display regionformed in the remaining region of the pixel. The first transparentsubstrate and the second transparent substrate may be formed such thatthe layer thickness of the liquid crystal layer in the reflectiondisplay region is thinner than the layer thickness of the liquid crystallayer in the transmission display region, and a columnar protrusion maybe formed on the surface facing the liquid crystal layer of at least oneof the first transparent substrate and the second transparent substrate,the columnar protrusion defining the substrate gap between the firsttransparent substrate and the second transparent substrate by protrudingfrom one of the substrates and abutting against the other substrate.

[0018] According to the present invention, in the first transparentsubstrate or the second transparent substrate, since the layer thicknessof the liquid crystal layer is made to be thinner in the reflectiondisplay region than the layer thickness of the liquid crystal layer inthe transmission display region, and even if the reflection displaylight passes through the liquid crystal layer twice while thetransmission display light is emitted out after passing through theliquid crystal layer only once, the retardation (Δn·d) can be enhancedor optimized in both of the transmission display light and thereflection display light. Further, by adjusting the thickness of theliquid crystal layer, even though an unevenness is formed on the firsttransparent substrate or the second transparent substrate, according tothe present invention, the substrate gap can be adjusted by the columnarprotrusion formed on the first transparent substrate or the secondtransparent substrate, and a gap material is not dispersed. Due to sucha structure, the non-uniformity of the substrate gap does not occur dueto the gap material coming into a concave portion of the unevennessformed by the layer-thickness adjusting layer between the firsttransparent substrate and the second transparent substrate, theretardation (Δn·d) can be held in an enhanced or optimum state.Therefore, a high quality display can be performed.

[0019] According to the present invention, in adjusting the thickness ofthe liquid crystal layer, for example, on the surface facing the liquidcrystal layer of the first transparent substrate, the total thickness ofthe films formed below the first electrode is thicker in the reflectiondisplay region than in the transmission display region. Further, on thesurface of the second transparent substrate facing the liquid crystallayer, the total thickness of the films formed below the secondelectrode can be thicker in the reflection display region than in thetransmission display region.

[0020] As structured above, for example, on the surface facing theliquid crystal layer of one transparent substrate of the firsttransparent substrate and the second transparent substrate, alayer-thickness adjusting layer is preferably formed, such that thelayer thickness of the liquid crystal layer in the reflection displayregion is thinner than the layer thickness of the liquid crystal layerin the transmission display region.

[0021] The layer-thickness adjusting layer is preferably formed on thesecond transparent substrate. That is, in the case that the firsttransparent substrate is a TFT array substrate, since a photolithographyprocess is performed on the TFT array substrate to form a TFT forswitching pixel or a light reflecting film, if a thick layer-thicknessadjusting layer is formed on the TFT array substrate, a considerabledifference of altitude or step occurs. As a result, the exposurepreciseness, etc. of the photolithography process is considerablylowered, and step fragments or film residues are generated. Accordingly,reliability or the production yield of the liquid crystal devicedecreases. However, according to the present invention, by forming thelayer-thickness adjusting layer on the second transparent substrate,that is, on the substrate in which the TFT to provide pixel switching isnot formed, the layer thickness of the liquid crystal layer in thereflection display region is made to be thinner than the layer thicknessof the liquid crystal layer in the transmission display region. Due tosuch a structure, even though the layer-thickness adjusting layer isprovided, the exposure preciseness in a photolithography process to forma pixel switching element on the first transparent substrate does notdecrease. Therefore, a transflective liquid crystal device having a highreliability and a high quality of display can be provided.

[0022] According to the present invention, the layer-thickness adjustinglayer is a transparent layer which is selectively formed in, forexample, the reflection display region in the pixel, or is a transparentlayer which is thickly formed in the reflection display region, and isformed thinner in the transmission display region than in the reflectiondisplay region.

[0023] According to the present invention, when performing a colordisplay, a color filter is formed in the pixel on the surface facing theliquid crystal layer of the second transparent substrate.

[0024] When forming such a color filter, a color filter for transmissiondisplay is preferably formed above or below the transparent layer in thetransmission display region in the pixel, and a color filter forreflection display is preferably formed in the reflection display regionon the same side as the color filter for transmission display for thetransparent layer.

[0025] Further, on the surface facing the liquid crystal layer of thesecond transparent substrate, a color filter for transmission display ispreferably formed above or below the transparent layer in thetransmission display region in the pixel, and a color filter forreflection display is preferably formed in the reflection display regionon the side opposite to the color filter for transmission display forthe transparent layer.

[0026] In the present invention, a chromaticity region of the colorfilter for transmission display is preferably wider than that of thecolor filter for reflection display. In the transflective liquid crystaldevice, since the reflection display light passes through the colorfilter twice while the transmission display light is emitted out afterpassing through the color filter only once, if the color filter fortransmission display is made to have a wider chromaticity region thanthe color filter for reflection display, images can be displayed withthe same color in both of the transmission display light and thereflection display light.

[0027] “A wide chromaticity region” in the specification of the presentinvention means that the area of a color triangle shown in, for example,a CIE1931rgb colorimetric system chromaticity diagram is large, and hasa dark color tone.

[0028] In the present invention, the color filter for transmissiondisplay preferably has a wide chromaticity region, for example, due todifferent kinds of color materials or blending amount from those of thecolor filter for reflection display. That is, if layer thickness of thecolor filter for transmission display is made to be thicker than that ofthe color filter for reflection display to widen the chromaticityregion, the effect by the layer-thickness adjusting layer can bedamaged. However, if the chromaticity region of the color filter fortransmission display is made to be wider than that of the color filterfor reflection display due to different kinds of color materials orblending amount, the damage of the effect by the layer-thicknessadjusting layer does not occur. On the contrary, layer thickness of thecolor filter for reflection display can be made to be thicker than thatof the color filter for transmission display, and therefore, the layerthickness balance of the liquid crystal layer between the transmissiondisplay region and the reflection display region can be enhanced oroptimized by the layer thickness difference of the color filters.

[0029] The layer-thickness adjusting layer of the present invention mayinclude a color filter for transmission display being thinly formed inthe transmission display region, and a color filter for reflectiondisplay being formed thicker in the reflection display region than thecolor filter for transmission display, of the pixel. Constructed asabove, the number of manufacturing processes does not increase since itis not necessary to newly add a layer-thickness adjusting layer.

[0030] In the present invention, when using the color filter as alayer-thickness adjusting layer, the color filter for transmissiondisplay may preferably include a first color material layer being thinand having a wide chromaticity region, and the color filter forreflection display may preferably include a second color material layerbeing thicker and having a narrower chromaticity region than the firstcolor material layer. In the transflective liquid crystal device, sincethe reflection display light passes through the color filter twice whilethe transmission display light is emitted out after passing through thecolor filter only once, if the color filter for transmission display ismade to have a wider chromaticity region than the color filter forreflection display, images can be displayed with the same color in bothof the transmission display light and the reflection display light.

[0031] Further, according to the present invention, the color filter fortransmission display may include a first color material layer, and thecolor filter for reflection display may include a first color materiallayer integrally formed with the color filter for transmission display,and a second color material layer formed above or below the first colormaterial layer.

[0032] The liquid crystal device according to the present invention canbe used as a display unit of an electronic apparatus, such as a mobilephone, a potable computer, etc.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033]FIG. 1 is a plan view of a transflective liquid crystal deviceaccording to the present invention as viewed at a counter substrate;

[0034]FIG. 2 is a sectional view of FIG. 1 taken along plane H-H′ ofFIG. 1;

[0035]FIG. 3 is a schematic circuit diagram showing component elements,etc. formed on a plurality of pixels in a matrix shape in thetransflective liquid crystal device;

[0036]FIG. 4 is a plan view showing the configuration of each pixel on aTFT array substrate of the transflective liquid crystal device accordingto the present invention;

[0037]FIG. 5 is a sectional view of the transflective liquid crystaldevice according to a first exemplary embodiment of the presentinvention taken along plane C-C′ of FIG. 4;

[0038]FIG. 6 is a sectional view of the transflective liquid crystaldevice according to a second exemplary embodiment of the presentinvention taken along plane C-C′ of FIG. 4;

[0039]FIG. 7 is a sectional view of the transflective liquid crystaldevice according to an exemplary modification of a second exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4;

[0040]FIG. 8 is a sectional view of the transflective liquid crystaldevice according to a third exemplary embodiment of the presentinvention taken along plane C-C′ of FIG. 4;

[0041]FIG. 9 is a sectional view of the transflective liquid crystaldevice according to an exemplary modification of a third exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4;

[0042]FIG. 10 is a sectional view of the transflective liquid crystaldevice according to a fourth exemplary embodiment of the presentinvention taken along plane C-C′ of FIG. 4;

[0043]FIG. 11 is a sectional view of the transflective liquid crystaldevice according to an exemplary modification of a fourth exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4;

[0044]FIG. 12 is a sectional view of the transflective liquid crystaldevice according to a fifth exemplary embodiment of the presentinvention taken along plane C-C′ of FIG. 4;

[0045]FIG. 13 is a sectional view of the transflective liquid crystaldevice according to a sixth exemplary embodiment of the presentinvention taken along plane C-C′ of FIG. 4;

[0046]FIG. 14 is a sectional view of the transflective liquid crystaldevice according to an exemplary modification of a sixth exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4;

[0047]FIG. 15 is a sectional view of the transflective liquid crystaldevice according to another exemplary modification of a sixth exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4;

[0048]FIG. 16 is a sectional view of the transflective liquid crystaldevice according to a seventh exemplary embodiment of the presentinvention taken along plane C-C′ of FIG. 4;

[0049]FIG. 17 is a sectional view of the transflective liquid crystaldevice according to an eighth exemplary embodiment of the presentinvention taken along plane C-C′ of FIG. 4;

[0050]FIG. 18 is a schematic of the circuits of the electronic apparatusemploying the transflective liquid crystal device according to thepresent invention as a display unit;

[0051]FIG. 19 is a schematic illustrating a portable personal computerusing the transflective liquid crystal device according to the presentinvention;

[0052]FIG. 20 is a schematic illustrating a mobile telephone using thetransflective liquid crystal device according to the present invention;

[0053]FIG. 21 is a sectional view of a related art transflective liquidcrystal device.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0054] Exemplary embodiments of the present invention are explained indetail below with reference to the drawings. Further, in the drawings ofthe following description, the scales of the respective layers ormembers are different, since each layer or member is just drawn with asize to be recognizable in the drawings.

[0055] [First Exemplary Embodiment]

[0056] (Basic Structure of a Transflective Liquid Crystal Device)

[0057]FIG. 1 is a plan view of a transflective liquid crystal deviceaccording to the present invention as viewed at component elements and acounter substrate, and FIG. 2 is a sectional view taken along plane H-H′of FIG. 1. FIG. 3 is a schematic circuit diagram showing variouselements, wirings, etc. in a plurality of pixels formed in a matrixshape in the image display region of the transflective liquid crystaldevice. Further, in the following description, the scales of layers ormembers in each of the drawings are different since each layer or memberis merely drawn with a size to be recognizable in the drawings.

[0058] As shown in FIGS. 1 and 2, a transflective liquid crystal device100 of the present invention is configured such that a liquid crystallayer 50 as an electric optical material is held between a TFT arraysubstrate 10 (a first transparent substrate) and a counter substrate 20(a second transparent substrate) which are sealed by a sealing material52, and a peripheral partition 53 made of a light shielding material isformed in the inner region of the portion formed by the sealing material52. A data line driving circuit 101 and a mounting terminal 102 areformed in the external region of the portion formed by the sealingmaterial 52 along one side of the TFT array substrate 10, and a scanningline driving circuit 104 is formed along two sides neighboring one siderespectively. A plurality of wirings 105 are provided on the rest of theone side of the TFT array substrate 10 to connect between the scanningline driving circuits 104 provided in both sides of the image displayregion, and additionally, a pre-charge circuit or a test circuit can beprovided by using the downside of the peripheral partition 53, or thelike. Further, an up-down conductive material 106 is formed on at leastone of the corner portions of the counter substrate 20 to provide anelectrical conduction between the TFT array substrate 10 and the countersubstrate 20. Further, the data line driving circuit 101 and thescanning line driving circuit 104, etc. can be overlapped with thesealing material 52, or can be formed in the portion in the inner regionof the sealing material 52.

[0059] Further, instead of forming the data line driving circuit 101 andthe scanning line driving circuit 104 on the TFT array substrate 10, forexample, a TAB (tape automated bonding) substrate having a driving LSIprovided thereon, can be provided to be electrically or mechanicallyconnected with a terminal group provided in the peripheral region of theTFT array substrate 10 through an anisotropic conductive film. Further,in the transflective liquid crystal device 100, a polarizing film, aphase difference film, a polarizing plate, etc. can be arranged in apredetermined direction according to the types of the liquid crystallayer 50 being used, that is, an operation mode, such as a TN (twistednematic) mode, a STN (super TN) mode, etc., or each of normally whitemode/normally black mode. However, the illustration thereof is omitted.Further, in the case of forming the transflective liquid crystal device100 for color display, each color filter of RGB is formed on the countersubstrate 20 along with its protecting film in the region facing eachpixel electrode 9 a on the TFT array substrate 10 as described below.

[0060] In the image display region of the transflective liquid crystaldevice 100 constructed as above, as shown in FIG. 3, a plurality ofpixels 100 a are formed in a matrix shape, and a pixel electrode 9 a anda TFT to provide pixel switching 30 to drive the pixel electrode 9 a areformed in each pixel 100 a, a data line 6 a to supply pixel signals S1,S2, . . . and Sn is electrically connected to the source of the TFT 30.The pixel signals S1, S2, . . . and Sn input to the data line 6 a can besupplied line-sequentially in this order, or can be supplied with groupfor a plurality of data lines 6 a neighboring each other. Further, ascanning line 3 a is electrically connected to the gate of the TFT 30,and scanning signals G1, G2, . . . and Gm are applied line-sequentiallyto the scanning line 3 a in this order in pulse at a predeterminedtiming. The pixel electrode 9 a is electrically connected to the drainof the TFT 30, and the pixel signals S1, S2, . . . and Sn supplied fromthe data line 6 a are written on each pixel at a predetermined timing bymaintaining the TFTs 30, which are switching elements, on-state only fora predetermined period. By doing so, the pixel signals S1, S2, . . . andSn of a predetermined level, written in the liquid crystal through thepixel electrode 9 a, are held between the pixel electrode 9 a and acounter electrode 21 of the counter substrate 20 for a predeterminedperiod.

[0061] The liquid crystal layer 50 changes the orientation or order ofthe molecular group according to the level of voltage applied to providethe light modulation and the gradation display. In a normally whitemode, the quantity of the incident light passing through the liquidcrystal layer 50 decreases according to the voltage applied. In anormally black mode, the quantity of the incident light passing throughthe liquid crystal layer 50 is increased according to the voltageapplied. As a result, the light having the contrast according to pixelsignals S1, S2, . . . and Sn is emitted from the transflective liquidcrystal device 100 as a whole.

[0062] Further, to reduce or prevent the leak of the held pixel signalsS1, S2, . . . and Sn, a storage capacitor 60 can be added parallel witha liquid crystal capacitor formed between the pixel electrode 9 a andthe counter electrode. For example, the voltage of the pixel electrode 9a is held by the storage capacitor 60 for a longer time as much as threedigit period than the time applied by the source voltage. By such astructure, the maintenance characteristic of the charges is enhanced,and the transflective liquid crystal device 100 having a high contrastratio can be realized. Further, as a method of forming the storagecapacitor 60, either method of forming between capacitor lines 3 b aswirings to form the storage capacitor 60, or method of forming betweenscanning lines 3 a of leading ends as shown in FIG. 3 can be employed.

[0063] (Structure of a TFT Array Substrate)

[0064]FIG. 4 is a plan view of a plurality of pixel groups neighboringeach other in the TFT array substrate used in the transflective liquidcrystal device of the present invention. FIG. 5 is a sectional view of apart of the pixel taken along plane C-C′ of FIG. 4.

[0065] In FIG. 4, pixel electrodes 9 a (first transparent electrode)made of a plurality of transparent ITO (Indium Tin Oxide) films areformed in a matrix shape on a TFT array substrate 10, and TFTs toprovide pixel switching 30 are connected to each pixel electrode 9 a.Further, data line 6 a, scanning line 3 a, and capacitor line 3 b areformed along the longitudinal and horizontal boundary of the pixelelectrode 9 a, and the TFT 30 is connected with the data line 6 a andthe scanning line 3 a. The data line 6 a is electrically connected in ahigh density source region 1 d through a contact hole, and theprotrusion portion of scanning line 3 a forms a gate electrode of theTFT 30. In addition, the storage capacitor 60 is configured such that anextension portion 1 f of a semiconductor film 1 to form the TFT forswitching pixel 30 becomes a lower electrode 41, and the capacitor line3 b as a upper electrode overlaps the lower electrode 41.

[0066] The sectional view of the pixel 100 a constructed as above takenalong plane C-C′ is shown in FIG. 5, a foundation protecting film 11made of a silicon oxide film (insulating film) of 300 to 500 nm inthickness is formed on the surface of a transparent substrate 10′ as abase substance of the TFT array substrate 10, and an island-shapedsemiconductor film 1 a of 30 to 100 nm in thickness is formed on thesurface of the foundation protecting film 11. A gate insulating film 2made of a silicon oxide film of about 50 to 150 nm in thickness isformed on the surface of the semiconductor film 1 a, and the scanningline 3 a of 300 to 800 nm in thickness is formed on the surface of thegate insulating film 2. In the semiconductor film 1 a, the region facingthe scanning line 3 a and having the gate insulating film 2 between themis a channel region 1 a′. In the channel region 1 a′, a source regionhaving a low density source region 1 b and a high density source region1 d is formed in a part thereof, and a drain region having a low densitydrain region 1 c and a high density drain region 1 e is formed in otherpart thereof.

[0067] An interlayer insulating film 4 made of a silicon oxide film of300 to 800 nm in thickness, is formed on the surface of the TFT toprovide pixel switching 30, and a surface protecting film (not shown)made of a silicon nitride film of 100 to 300 nm in thickness, may beformed on the surface of the interlayer insulating film 4. A data line 6a, being 300 to 800 nm in thickness, is formed on the surface of theinterlayer insulating film 4, and the data line 6 a is electricallyconnected to a high density source region 1 d through the contact holeformed on the interlayer insulating film 4. A drain electrode 6 b,formed together with the data line 6 a, is formed on the surface of theinterlayer insulating film 4, and the drain electrode 6 b iselectrically connected to a high density drain region 1 e through thecontact hole formed on the interlayer insulating film 4.

[0068] An unevenness forming layer 13 a made of a first photosensitiveresin, is formed on the upper surface of the interlayer insulating film4 with a predetermined pattern, and an upper-layer insulating film 7 amade of a second photosensitive resin, is formed on the layer of theunevenness forming layer 13 a. In addition, a light reflecting film 8 amade of an aluminum film, etc., is formed on the surface of theupper-layer insulating film 7 a. Therefore, an unevenness pattern 8 g isformed on the surface of the light reflecting film 8 a, the patternhaving a concave portion 8 c and a convex portion 8 b by reflecting theunevenness of an unevenness forming layer 13 a through the upper-layerinsulating film 7 a.

[0069] A light transmitting window 8 d is formed on the light reflectinglayer 8 a. Due to such a structure, the light reflecting film 8 a formsa reflection display region 100 b in the pixel region 100 a in which thepixel electrode 9 a faces the counter electrode 21. Further, theremaining region in which the light reflecting film 8 a is not formed(light transmitting window 8 d) forms a transmission display region 100c.

[0070] The pixel electrode 9 a made of an ITO film, is formed above thelight reflecting film 8 a. The pixel electrode 9 a is directly laminatedon the surface of the light reflecting film 8 a, and the pixel electrode9 a is electrically connected to the light reflecting film 8 a. Further,the pixel electrode 9 a is electrically connected to the drain electrode6 b through the contact hole formed on the photosensitive resin layer 7a and the interlayer insulating film 4.

[0071] An oriented layer 12 made of polyimide film is formed on thesurface of the pixel electrode 9 a. The oriented layer 12 is a film inwhich a rubbing-treatment is performed for the polyimide film.

[0072] Further, a capacitor line 3 b as an upper electrode faces theextension portion If (lower electrode) extended from the high densitydrain region 1 e through an insulating film (dielectric film) formedtogether with the gate insulating film 2 to form a storage capacitor 60.

[0073] Further, this exemplary embodiment forms a plurality of columnarprotrusion 40, of 2 to 3 μm in height and including transparentpolyimide resin, etc. in each pixel 100 a above the capacitor line 3 b,and the interval between the TFT array substrate 10 and the countersubstrate 20 is defined by such a columnar protrusion 40. Due to such astructure, a gap material is not dispersed between the TFT arraysubstrate 10 and the counter substrate 20 in the transflective liquidcrystal device 100 of the present invention.

[0074] Further, the TFT 30 preferably has an LDD structure as describedabove, or may have an off-set structure in which impurity ions are notinjected in a region corresponding to a low density source region 1 band a low density drain region 1 c. Further, the TFT 30 may be aself-align typed TFT in which a high density of impurity ions areinjected using a gate electrode (a part of a scanning line 3 a) as amask, and a high density source and drain regions are formed in aself-matching manner.

[0075] Further, this exemplary embodiment has a single gate structuresuch that one gate electrode (scanning line 3 a) of the TFT 30 isarranged between the source and the drain regions, but two or more gateelectrodes can be arranged between them. In such a case, an identicalsignal is applied on each gate electrode. As above, if the TFT 30 has astructure of a dual-gate (double gate) or a triple gate or more, it ispossible to reduce or prevent leak current in the connection portion ofthe channel and the source-drain regions, and is possible to reducecurrent in off-state. If at least one of the gate electrodes is made inan LDD structure or an in off-set structure, the off-set current can befurther reduced, and a stable switching device can be achieved.

[0076] (Structure of a Counter Substrate)

[0077] The counter substrate 20 is configured such that a lightshielding film 23, which is referred to as a black matrix or a blackstripe, etc., is formed in the region facing the longitudinal andhorizontal boundary portion of the pixel electrode 9 a formed on the TFTarray substrate 10, and the counter electrode 21 (a second electrode)made of an ITO film, is formed above the light shielding film 23. Analignment film 22, made of a polyimide film, is formed above the counterelectrode 21, and the alignment film 22 is a film in which a rubbingtreatment is performed for the polyimide film.

[0078] Further, below the counter electrode 21 of the counter substrate20, RGB color filters 24, of 1 to several μm in thickness, are formed byusing a photolithography technology, a flexographic printing or ink jetprinting, in the reflection display region 100 b and the transmissiondisplay region 100 c. The color filters 24 are integrally formed in thereflection display region 100 b and the transmission display region 100c, and the thickness thereof is uniform in the reflection display region100 b and the transmission display region 100 c.

[0079] Further, in this exemplary embodiment, a layer-thicknessadjusting layer 25 is formed between the counter electrode 21 and thecolor filter 24, that is, below the counter electrode 21 such that thelayer thickness “d” of the liquid crystal layer 50 in the reflectiondisplay region 100 b becomes thinner than the layer thickness “d” of theliquid crystal layer 50 in the transmission display region 100 c. Inthis exemplary embodiment, the layer-thickness adjusting layer 25 is atransparent layer, of 2 to 3 μm in thickness and made of acryl resin orpolyimide resin, etc., which is selectively formed in the reflectiondisplay region 100 b by using a photolithography technology, aflexographic printing or ink jet printing.

[0080] (Operation and Effect of the Invention)

[0081] Therefore, in the liquid crystal structured as above, with regardto the light emitted from a backlight apparatus (not shown) disposed onthe back side of the TFT array substrate 10, as the light incident intothe transmission display region 100 c, as indicated by arrow LB, thelight is incident from the TFT array substrate 10 into the liquidcrystal layer 50, and after it is light-modulated in the liquid crystallayer 50, it is emitted from the counter substrate 20 as a transmissiondisplay light to display images (transmission mode).

[0082] Further, with regard to the external light incident from thecounter substrate 20, as the light incident into the reflection displayregion 100 b, as indicated by LA, the light passes through the liquidcrystal layer 50, reaches the light reflecting film 8 a, is reflectedfrom the light reflecting film 8 a, passes through the liquid crystallayer 50 again, emitted from the counter substrate 20 as a reflectingdisplay light to display images (reflection mode).

[0083] When performing such display, the reflection display light passesthrough the liquid crystal layer 50 twice, while the transmissiondisplay light is emitted by passing through the liquid crystal layer 50just once, but in this exemplary embodiment, by the layer-thicknessadjusting layer 25 formed in the reflection display region 100 b, thelayer thickness “d” of the liquid crystal layer 50 in the reflectiondisplay region 100 b is formed considerably thinner than the layerthickness “d” of the liquid crystal layer 50 in the transmission displayregion 100 c. Due to such a structure, the retardation (Δn·d) can beenhanced or optimized in both of the transmission display light and thereflection display light so as to perform a high quality display.

[0084] Further, in this exemplary embodiment, the layer-thicknessadjusting layer 25 is formed on the counter substrate 20, that is, onthe substrate in which a TFT for switching pixel 30 is not formed sothat the layer thickness “d” of the liquid crystal layer 50 in thereflection display region 100 b becomes thinner than the layer thickness“d” of the liquid crystal layer 50 in the transmission display region100 c. Due to such a structure, even though the layer-thicknessadjusting layer 25 is provided, the exposure preciseness in aphotolithography process to form the TFT 30 on the TFT array substrate10 is not lowered. Therefore, the transflective liquid crystal device100 having a high reliability and a high quality of display can beprovided.

[0085] Further, in this exemplary embodiment, the interval between theTFT array substrate 10 and the counter substrate 20 is defined by acolumnar protrusion 40 formed on the TFT array substrate 10, and a gapmaterial is not dispersed between the TFT array substrate 10 and thecounter substrate 20. Due to such a structure, even though an unevennessexists on the counter substrate 20 due to the layer-thickness adjustinglayer 25 like the shape in this exemplary embodiment, a problem in whichthe device does not fulfill its function due to the gap materialremaining in a concave portion, does not occur. Therefore, since thepreciseness of the interval between the TFT array substrate 10 and thecounter substrate 20 can be well defined, and the retardation (Δn·d) canbe enhanced or optimized, accordingly a display can have a high quality.

[0086] Further, this exemplary embodiment provides an advantage that thelayer-thickness adjusting layer 25 does not cause the non-uniformity ofthe film thickness of the color filter 24 even though the color filter24 is formed by using a spin coating method, since the color filter 24is formed before the layer-thickness adjusting layer 25 is formed.

[0087] [Second Exemplary Embodiment]

[0088]FIG. 6 is a sectional view of a part of the pixel of thetransflective liquid crystal device according to a second exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4.Further, in the configuration of this exemplary embodiment and anyconfiguration to be described below, a basic structure is the same asthat of the first exemplary embodiment. Therefore, the common elementsare designated with the same numerals to omit the description thereof,and only the structure of a counter substrate which is a feature of eachexemplary embodiment are explained.

[0089] On a counter substrate 20 shown in FIG. 6, the layer thickness“d” of a liquid crystal layer 50 in a reflection display region 100 b isconsiderably thinner than the layer thickness “d” of a liquid crystallayer 50 in a transmission display region 100 c by a transparentlayer-thickness adjusting layer 25 selectively formed in the reflectiondisplay region 100 b. Due to such a structure, the retardation (Δn·d)can be enhanced or optimized in both of the transmission display lightand the reflection display light so as to perform a high qualitydisplay.

[0090] Further, in this exemplary embodiment, the layer-thicknessadjusting layer 25 is formed on the counter substrate 20, that is, onthe substrate in which a TFT to provide pixel switching 30 is not formedso that the layer thickness “d” of the liquid crystal layer 50 in thereflection display region 100 b becomes thinner than the layer thickness“d” of the liquid crystal layer 50 in the transmission display region100 c. Due to such a structure, even though the layer-thicknessadjusting layer 25 is provided, the exposure preciseness in aphotolithography process for forming the TFT 30 on the TFT arraysubstrate 10 is not lowered. Therefore, the transflective liquid crystaldevice 100 having a high reliability and a high quality display can beprovided.

[0091] Further in this exemplary embodiment, the interval between theTFT array substrate 10 and the counter substrate 20 is defined by thecolumnar protrusion 40 formed on the TFT array substrate 10, and a gapmaterial is not dispersed between the TFT array substrate 10 and thecounter substrate 20. Due to such a structure, even though a unevennessexists on the counter substrate 20 due to the layer-thickness adjustinglayer 25 like the shape in this exemplary embodiment, a problem in whichthe device does not fulfill its function due to a gap material remainingin a concave portion, does not occur. Therefore, since the precisenessof the interval between the TFT array substrate 10 and the countersubstrate 20 can be well defined, and the retardation (Δn·d) can beenhanced or optimized, accordingly a display can have a high quality.

[0092] Further, RGB color filters are formed in the reflection displayregion 100 band the transmission display region 100 c below the counterelectrode 21, and the color filter in this exemplary embodiment means acolor filter for transmission display 241 formed in the transmissiondisplay region 100 c, and a color filter for reflection display 242formed in the reflection display region 100 b, and they have the samefilm thickness, but the color filter for transmission display 241 has awider chromaticity region than the color filter for reflection display242 since they have different color materials or blending amount.

[0093] Therefore, in the transflective liquid crystal device 100, whilethe transmission display light is emitted by passing the color filteronce, the reflection display light passes through the color filtertwice. However, since the chromaticity region of the color filter fortransmission display 241 is wider than that of the color filter forreflection display 242, images can be displayed with the same color inboth of the transmission display light and the reflection display light.

[0094] If the color filter for transmission display 241 is made to bethicker than the color filter for reflection display 242, such that thechromaticity region of the color filter for transmission display 241becomes wider than that of the color filter for reflection display 242,the effect by the layer-thickness adjusting layer 25 can be damaged.However, in this exemplary embodiment, since the chromaticity region ofthe color filter for transmission display 241 is made to be wider thanthat of the color filter for reflection display 242 according to thekinds of color materials or blending amount, damage to the effect oflayer-thickness adjusting layer 25 is not caused.

[0095] On the contrary, as shown in FIG. 7, by making the film thicknessof the color filter for reflection display 242 thicker than that of thecolor filter for transmission display 241, the layer thickness balanceof the liquid crystal layer 50 between the transmission display region100 c and the reflection display region 100 b can be enhanced oroptimized by the layer thickness difference of the color filters 241,242 in addition to the layer-thickness adjusting layer 25.

[0096] [Third Exemplary Embodiment]

[0097]FIG. 8 is a sectional view of a part of the pixel of thetransflective liquid crystal device according to a third exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4.

[0098] In the first and second exemplary embodiments, thelayer-thickness adjusting layer 25 is formed between the counterelectrode 21 and the color filter. However, in this exemplaryembodiment, as shown in FIG. 8, a transparent layer-thickness adjustinglayer 25 is selectively formed in a reflection display region 100 bbelow a color filter for transmission display 241 formed in atransmission display region 100 c, and a color filter for reflectiondisplay 242 formed in a reflection display region 100 b.

[0099] Due to such a structure, the layer thickness “d” of a liquidcrystal layer 50 in a reflection display region 100 b is considerablythinner than the layer thickness “d” of a liquid crystal layer 50 in atransmission display region 100 c. Therefore, the retardation (Δn·d) canbe enhanced or optimized in both of the transmission display light andthe reflection display light so as to perform a high quality display.Further, in this exemplary embodiment, by forming the layer-thicknessadjusting layer 25 on the counter substrate 20, that is, on the surfacein which the TFT to provide pixel switching 30 is not formed, since thelayer thickness “d” of the liquid crystal layer 50 in the reflectiondisplay region 100 b is made to be thinner than the layer thickness “d”of the liquid crystal layer 50 in the transmission display region 100 c,even though the layer-thickness adjusting layer 25 is provided, theexposure preciseness in a photolithography process to form the TFT 30 onthe TFT array substrate 10 is not lowered. Therefore, the transflectiveliquid crystal device 100 having a high reliability and a high qualityof display can be provided.

[0100] Further, also in this exemplary embodiment, a chromaticity regionof the color filter for transmission display 241 is wider than that ofthe color filter for reflection display 242. Therefore, images can bedisplayed with the same colors in both of the transmission display lightand the reflection display light.

[0101] Further, since the interval between the TFT array substrate 10and the counter substrate 20 is defined by a columnar protrusion 40formed on the TFT array substrate 10, and a gap material is notdispersed between the TFT array substrate 10 and the counter substrate20, even though an unevenness exists on the counter substrate 20 due tothe layer-thickness adjusting layer 25, a problem in which the devicedoes not fulfill its function due to the gap material remaining in aconcave portion, does not occur. Therefore, since the preciseness of theinterval between the TFT array substrate 10 and the counter substrate 20can be well defined, and the retardation (Δn·d) can be enhanced oroptimized. Accordingly a display can have a high quality.

[0102] Further, in this exemplary embodiment, a chromaticity region ofthe color filter for transmission display 241 is wider than that of thecolor filter for reflection display 242. However, as shown in FIG. 9,the common color filter 24 can be formed in the reflection displayregion 100 b and the transmission display region 100 c.

[0103] [Fourth Exemplary Embodiment]

[0104]FIG. 10 is a sectional view of a part of the pixel of thetransflective liquid crystal device according to a fourth exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4.

[0105] In the first and second exemplary embodiments, thelayer-thickness adjusting layer 25 is formed between the counterelectrode 21 and the color filter, and in the third exemplaryembodiment, the layer-thickness adjusting layer 25 is formed below thecolor filter. However, in this exemplary embodiment, as shown in FIG.10, a transparent layer-thickness adjusting layer 25 is selectivelyformed in a reflection display region 100 b above a color filter fortransmission display 241 formed in a transmission display region 100 c,and a color filter for reflection display 242 is formed above thelayer-thickness adjusting layer 25.

[0106] Also, in the transflective liquid crystal device 100 structuredas above, the layer thickness “d” of a liquid crystal layer 50 in thereflection display region 100 b is considerably thinner than the layerthickness “d” of a liquid crystal layer 50 in the transmission displayregion 100 c. Therefore, the retardation (Δn·d) can be enhanced oroptimized in both of the transmission display light and the reflectiondisplay light so as to perform a high quality display. Further, in thisexemplary embodiment, by forming a layer-thickness adjusting layer 25 ona counter substrate 20, that is, on the surface which a TFT to providepixel switching 30 is not formed, since the layer thickness “d” of theliquid crystal layer 50 in the reflection display region 100 b is madeto be thinner than the layer thickness “d” of the liquid crystal layer50 in the transmission display region 100 c, even though thelayer-thickness adjusting layer 25 is provided, the exposure precisenessin a photolithography process to form the TFT 30 on the TFT arraysubstrate 10 is not lowered. Therefore, the transflective liquid crystaldevice 100 having a high reliability and a high quality of display canbe provided.

[0107] Further, in this exemplary embodiment, a chromaticity region ofthe color filter for transmission display 241 is wider than that of thecolor filter for reflection display 242. Therefore, images can bedisplayed with the same colors in both of the transmission display lightand the reflection display light.

[0108] Further, since the interval between the TFT array substrate 10and the counter substrate 20 is defined by a columnar protrusion 40formed on the TFT array substrate 10, and a gap material is notdispersed between the TFT array substrate 10 and the counter substrate20, even though an unevenness exists on the counter substrate 20 due tothe layer-thickness adjusting layer 25, a problem in which the devicedoes not fulfill its function due to the gap material remaining in aconcave portion, does not occur. Therefore, since the preciseness of theinterval between the TFT array substrate 10 and the counter substrate 20can be well defined, and the retardation (Δn·d) can be enhanced oroptimized, accordingly a display can have a high quality.

[0109] Further, in this exemplary embodiment, a chromaticity region ofthe color filter for transmission display 241 is wider than that of thecolor filter for reflection display 242. However, as shown in FIG. 11,color filters 241, 242 having the identical layer thickness andchromaticity region for the transmission display region 100 c and thereflection display region 100 b can be formed.

[0110] [Fifth Exemplary Embodiment]

[0111]FIG. 12 is a sectional view of a part of the pixel of thetransflective liquid crystal device according to a fifth exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4.

[0112] In the first, second, third and fourth exemplary embodiments, thelayer-thickness adjusting layer 25 is selectively formed in reflectiondisplay region 100 b, but for example, as shown in FIG. 12, atransparent layer being thin in a transmission display region 100 c andbeing thick in a reflection display region 100 b can be used as alayer-thickness adjusting layer 25. The layer-thickness adjusting layer25 structured as above can be formed by a method of forming thetransparent layer twice by a photolithography technology, a flexographicprinting or ink jet printing, or by a photolithography technology ofperforming a half exposure.

[0113] [Sixth Exemplary Embodiment]

[0114]FIG. 13 is a sectional view of a part of the pixel of thetransflective liquid crystal device according to a sixth exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4.

[0115] Each of the first to fifth exemplary embodiments provides astructure in which the layer-thickness adjusting layer 25 is formedbelow the counter electrode 21 as a transparent layer. However, in thesixth and seventh exemplary embodiments described below, a color filteritself can be used as a layer-thickness adjusting layer.

[0116] As shown in FIG. 13, the transflective liquid crystal device 100of this exemplary embodiment has a thin color filter for transmissiondisplay 241 formed on a transmission display region 100 c, and a thickcolor filter for reflection display 242 formed on a reflection displayregion 100 b by using a photolithography technology, a flexographicprinting or ink jet printing for a lower side of a counter electrode 21.

[0117] Due to such a structure, the layer thickness “d” of a liquidcrystal layer 50 in a reflection display region 100 b is considerablythinner than the layer thickness “d” of a liquid crystal layer 50 in atransmission display region 100 c. Therefore, the retardation (Δn·d) canbe enhanced or optimized in both of the transmission display light andthe reflection display light so as to perform a high quality display.Further, in this exemplary embodiment, by forming the layer-thicknessadjusting layer 25 on the counter substrate 20, that is, on the surfacewhich the TFT to provide pixel switching 30 is not formed on, since thelayer thickness “d” of the liquid crystal layer 50 in the reflectiondisplay region 100 b is made thinner than the layer thickness “d” of theliquid crystal layer 50 in the transmission display region 100 c, eventhough the layer-thickness adjusting layer 25 is provided, the exposurepreciseness in a photolithography process to form the TFT 30 on the TFTarray substrate 10 is not lowered. Therefore, the transflective liquidcrystal device 100 having a high reliability and a high quality ofdisplay can be provided.

[0118] Further, in this exemplary embodiment, the chromaticity region ofa color filter for transmission display 241 is wider than that of thecolor filter for reflection display 242 according to the kinds of colormaterials or blending amount. Therefore, images can be displayed withthe same colors in both of the transmission display light and thereflection display light.

[0119] Also in this exemplary embodiment, since the interval between theTFT array substrate 10 and the counter substrate 20 is defined by acolumnar protrusion 40 formed on the TFT array substrate 10, and a gapmaterial is not dispersed between the TFT array substrate 10 and thecounter substrate 20, even though an unevenness exists on the countersubstrate 20 due to the layer-thickness adjusting layer 25, a problem inwhich the device does not fulfill its function due to the gap materialremaining in a concave portion, does not occur. Therefore, since thepreciseness of the interval between the TFT array substrate 10 and thecounter substrate 20 can be well defined, and the retardation (Δn·d) canbe enhanced or optimized, accordingly a display can have a high quality.

[0120] Further, in this exemplary embodiment, a chromaticity region ofthe color filter for transmission display 241 is wider than that of thecolor filter for reflection display 242. However, as shown in FIG. 14,color filters 241, 242, each including identical color materials butbeing different in the layer thickness, can be formed respectively inthe transmission display region 100 c and the reflection display region100 b.

[0121] Further, as shown in FIG. 15, a structure in which a color filter241 (a first color material layer), having the same chromaticity regionand layer thickness as on the transmission display region 100 c, and acolor filter 242 (a second color material layer), including thedifferent color material, are laminated on the reflection display region100 b can be employed so as to make a difference in the layer thickness.

[0122] [Seventh Exemplary Embodiment]

[0123]FIG. 16 is a sectional view of a part of the pixel of thetransflective liquid crystal device according to a seventh exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4.

[0124] In the first to sixth exemplary embodiments, the layer-thicknessadjusting layer 25 is formed on the counter substrate 20. However, asshown in FIG. 16, a layer-thickness adjusting layer 15, made of aphotosensitive resin, can be selectively formed on a reflection displayregion 100 b of a TFT array substrate 10 by using a photolithographytechnology, a flexographic printing method or ink jet printing method soas to enhance or optimize the retardation (Δn·d) in both of thetransmission display light and the reflection display light.

[0125] Further, in the example shown in FIG. 16, the layer-thicknessadjusting layer 15 is formed below an unevenness forming layer 13 a.However, the layer-thickness adjusting layer 15 can be formed betweenany layers, only if it is the lower side of a pixel electrode 9 a.Further, if an interlayer adjusting layer 15 is formed below the lightreflecting film 8 a, the layer-thickness adjusting layer 15 does notneed to be limited to a transparent film.

[0126] [Eighth Exemplary Embodiment]

[0127]FIG. 17 is a sectional view of a part of the pixel of thetransflective liquid crystal device according to an eighth exemplaryembodiment of the present invention taken along plane C-C′ of FIG. 4.

[0128] In the first to seventh exemplary embodiments, the retardation(Δn·d) in both of the transmission display light and the reflectiondisplay light is enhanced or optimized by adding the layer-thicknessadjusting layers 15, 25. However, for example, as shown in FIG. 17, byeliminating an upper-layer insulating film 7 a on the transmissiondisplay region 100 c of the TFT array substrate 10, the total thicknessof the films formed below the pixel electrode 9 a is thick on thereflection display region 100 b, and is thin on the transmission displayregion 100 c so that the layer thickness “d” of a liquid crystal layer50 can be adjusted.

[0129] [Other Exemplary Embodiments]

[0130] In the above exemplary embodiments, the examples of performingthe adjustment of the substrate gap by the columnar protrusion 40 in theliquid crystal device having the layer-thickness adjusting layer 25formed on the counter substrate 20 are illustrated. However, theadjustment of the substrate gap by the columnar protrusion 40 can bealso performed in the liquid crystal device having the layer-thicknessadjusting layer 25 formed on the TFT array substrate 10.

[0131] Further, the columnar protrusion 40 can be formed on the countersubstrate 20.

[0132] Furthermore, in the above exemplary embodiments, the example ofusing a TFT as an active device for switching pixel is illustrated.However, a thin film diode device (TFD device), such as an MIM device(Metal Insulator Metal device), etc. as an active device in the same waycan be also employed.

[0133] [Application of the Transflective Liquid Crystal Device in anElectronic Apparatus]

[0134] The transflective liquid crystal device 100 structured as abovecan be used as a display unit of various electronic apparatus, and theexamples are explained in reference to FIGS. 18-20.

[0135]FIG. 18 is a schematic of the circuits of the electronic apparatususing the transflective liquid crystal device according to the presentinvention as a display unit.

[0136] In FIG. 18, the electronic apparatus includes an output source ofdisplay information 70, a display information processing circuit 71, apower source circuit 72, a timing generator 73, and a liquid crystaldevice 74. In addition, the liquid crystal device 74 includes a liquidcrystal display panel 75 and a driving circuit 76. The transflectiveliquid crystal device 100 as described above can be used as the liquidcrystal device 74.

[0137] The output source of display information 70 includes a memory,such as an ROM (Read Only Memory), an RAM (Random Access Memory), etc.,a storage unit, such as various disks, etc., and a tuning circuit totune-output digital image signals, or the like, and display information,such as image signals in a predetermined format, is supplied to thedisplay information processing circuit 71 according to various clocksignals generated by the timing generator 73.

[0138] The display information processing circuit 71 includes relatedart, later developed or widely-known various circuits, such as aserial-parallel conversion circuit, an amplification·inversion circuit,a rotation circuit, a gamma correction circuit, a clamp circuit, etc.,for example, and performs the processing of input display information soas to supply the image signal to the driving circuit 76 along with theclock signal (CLK). The power source circuit 72 supplies a predeterminedvoltage to each component element.

[0139]FIG. 19 illustrates a portable personal computer as one example ofthe electronic apparatus according to the present invention. Thepersonal computer 80 includes a body unit 82 having a keyboard 81, and aliquid crystal display unit 83. The liquid crystal display unit 83 isstructured to include the transflective liquid crystal device 100 asdescribed above.

[0140]FIG. 20 illustrates a mobile phone as another example of theelectronic apparatus according to the present invention. The mobilephone 90 includes a plurality of manipulating buttons 91 and a displayunit provided with the transflective liquid crystal device 100 asdescribed above.

[0141] [Effects of the Invention]

[0142] As described above, according to the present invention, since thelayer thickness of the liquid crystal layer in the reflection displayregion is made to be thinner than the layer thickness of the liquidcrystal layer in the transmission display region on the firsttransparent substrate and the second transparent substrate, even thoughthe reflection display light passes through the liquid crystal layertwice while the transmission display light is emitted out after passingthrough the liquid crystal layer only once, the retardation (Δn·d) canbe enhanced or optimized in both of the transmission display light andthe reflection display light. Further, in the present invention, eventhough an unevenness is formed on the surface of the first transparentsubstrate or the second transparent substrate by adjusting the thicknessof the liquid crystal layer, the substrate gap can be adjusted by thecolumnar protrusion formed on the first transparent substrate or thesecond transparent substrate, and a gap material is not dispersed. Dueto such a structure, the non-uniformity of the substrate gap does notoccur due to a gap material coming into a concave portion of theunevenness due to the layer-thickness adjusting layer between the firsttransparent substrate and the second transparent substrate, theretardation (Δn·d) can be held in an enhanced or optimum state.Therefore, a high quality of display can be performed.

What is claimed is:
 1. A transflective liquid crystal device,comprising: a first transparent substrate having first transparentelectrodes and pixel switching elements formed on a surface in a matrix;a second transparent substrate having second transparent electrodesformed on a surface facing the first transparent electrodes; a liquidcrystal layer held between the first transparent substrate and thesecond transparent substrate; a light reflecting layer formed on thefirst transparent substrate, the light reflecting layer having areflection display region formed in a pixel in which the firsttransparent electrode faces the second transparent electrode and atransmission display region formed in the remaining region of the pixel,the first transparent substrate and the second transparent substratebeing formed such that a layer thickness of the liquid crystal layer inthe reflection display region is thinner than the layer thickness of theliquid crystal layer in the transmission display region; and a columnarprotrusion formed on a surface facing the liquid crystal layer of atleast one of the first transparent substrate and the second transparentsubstrate, the columnar protrusion defining the substrate gap betweenthe first transparent substrate and the second transparent substrate byprotruding from one of the substrates and abutting against the othersubstrate.
 2. The transflective liquid crystal device according to claim1, on the surface of the second transparent substrate facing the liquidcrystal layer, the total thickness of the films formed below the secondelectrode being thicker in the reflection display region than in thetransmission display region.
 3. The transflective liquid crystal deviceaccording to claim 1, on the surface of the first transparent substratefacing the liquid crystal layer, the total thickness of the films formedbelow the first electrode being thicker in the reflection display regionthan in the transmission display region.
 4. The transflective liquidcrystal device according to claim 1, a layer-thickness adjusting layerbeing formed on the surface facing the liquid crystal layer of onetransparent substrate of the first transparent substrate and the secondtransparent substrate such that the layer thickness of the liquidcrystal layer in the reflection display region becomes thinner than thelayer thickness of the liquid crystal layer in the transmission displayregion.
 5. The transflective liquid crystal device according to claim 4,the layer-thickness adjusting layer being formed on the secondtransparent substrate.
 6. The transflective liquid crystal deviceaccording to claim 5, the layer-thickness adjusting layer being atransparent layer which is selectively formed in the reflection displayregion.
 7. The transflective liquid crystal device according to claim 5,the layer-thickness adjusting layer being a transparent layer which isthickly formed in the reflection display region, and being formedthinner in the transmission display region than in the reflectiondisplay region.
 8. The transflective liquid crystal device according toclaim 6, a color filter being formed in the pixels on the surface of thesecond transparent substrate facing the liquid crystal layer.
 9. Thetransflective liquid crystal device according to claim 6, on the surfaceof the second transparent substrate facing the liquid crystal layer, acolor filter for transmission display being formed above or below thetransparent layer in the transmission display region in the pixel, and acolor filter for reflection display being formed in the reflectiondisplay region on the same side as the color filter for transmissiondisplay for the transparent layer.
 10. The transflective liquid crystaldevice according to claim 6, on the surface of the second transparentsubstrate facing the liquid crystal layer, a color filter fortransmission display being formed above or below the transparent layerin the transmission display region in the pixel, and a color filter forreflection display being formed on the side opposite to the color filterfor transmission display for the transparent layer in the reflectiondisplay region.
 11. The transflective liquid crystal device according toclaim 9, a chromaticity region of the color filter for transmissiondisplay being wider than that of the color filter for reflectiondisplay.
 12. The transflective liquid crystal device according to claim11, the color filter for transmission display having a wide chromaticityregion due to different kinds of color materials or blending amount fromthose of the color filter for reflection display.
 13. The transflectiveliquid crystal device according to claim 9, the film thickness of thecolor filter for transmission display being the same as the filmthickness of the color filter for reflection display.
 14. Thetransflective liquid crystal device according to claim 9, the layerthickness of the color filter for reflection display being thicker thanthe layer thickness of the color filter for transmission display. 15.The transflective liquid crystal device according to claim 5, thelayer-thickness adjusting layer including a color filter fortransmission display which is thinly formed in the transmission displayregion, and a color filter for reflection which is formed thicker in thereflection display region than the color filter for transmission displayin the pixel.
 16. The transflective liquid crystal device according toclaim 15, the color filter for transmission display being formed from afirst color material layer which is thin and has a wide chromaticityregion, and the color filter for reflection display being formed from asecond color material layer which is thicker than and has a narrowerchromaticity region than the first color material layer.
 17. Thetransflective liquid crystal device according to claim 15, the colorfilter for transmission display being formed from a first color materiallayer, and the color filter for reflection display being formed from afirst color material layer integrally formed with the color filter fortransmission display, and a second color material layer being laminatedabove or below the first color material layer.
 18. An electronicapparatus, comprising: a display unit including the transflective liquidcrystal device according to claim 1.